This invention relates to foam insulating products, particularly extruded polystyrene foam, containing a minor amount of one or more additives including, for example, one or more vinyl resins, sufficient to achieve a desired combination of flexibility and strength. The rigid extruded polystyrene foam boards manufactured according to the invention can be deformed repeatedly at room temperature in the process of creating shaped board forms having one or more curvatures, bends or deformations, without resiling, cracking or breaking, while substantially retaining the thermal and physical properties of the original, non-deformed board.
As will be appreciated, the ability to deform expanded foam insulation boards into various shapes to fit within the architectural design of a structure while tending to preserve its structural and insulating integrity is particularly advantageous for construction applications. This ability is also desirable for expanded foam insulation boards intended for use as exterior wall insulation board or as highway underground insulation board for concrete structures having waved, curved, oscillating or other rounded complex profiles.